In the drilling and completion of oil wells, gas wells and similar boreholes, it is frequently desirable to transmit data representative of various downhole conditions from a subsurface location to a surface location. In one borehole system, downhole measurements are transmitted by means of an electrical conductor or cable extending upward to the surface of the earth through the drill string (see U.S. Pat. No. 3,068,447 to J. K. Godbey). In another borehole system, a downhole measurement is transmitted uphole by means of an acoustic wave pa-sing upward through the drill string (see U.S. Pat. No. 2,810,546 to B. G. Eaton). In yet another borehole system, drilling mud within the borehole is utilized as the transmission medium for information-bearing acoustic waves (see U.S. Pat. No 3,309,656 to J. K. Godbey). An acoustic transmitter located downhole continuously interrupts the flow of drilling mud, thereby generating an acoustic signal in the drilling mud. The acoustic wave is modulated with the downhole measurement at the surface. At the surface the acoustic signal is detected and demodulated to provide the desired readout information.
Each of these borehole measurement transmission mediums can be disruptive to other borehole operations. It is, therefore, a specific object of the present invention to provide for a borehole temperature measuring method and apparatus, particularly for temperature, which overcomes the shortcomings of such downhole parameter measurement and data transmission techniques so as to be non-disruptive to other borehole operations.